1. Field of the Invention
The present invention relates to liquid crystal shutter glasses.
2. Description of Prior Art
A three-dimensional image display system by which a viewer with liquid crystal shutter glasses can view stereoscopic image is well-known. The three-dimensional image display system alternately displays images for a right eye and images for a left eye on a screen in a determined period. (The term "3D display" in this specification indicates the above type of display.) As regarding liquid crystal shutter glasses on which a viewer puts, liquid crystal for a right eye and liquid crystal for a left eye alternately transmit light and do not transmit light respectively in synchronization with the determined period.
FIG. 10A is a plan view showing the conventional liquid crystal shutter glasses. FIG. 10B is a perspective view showing the conventional liquid crystal shutter glasses, as seen from the front side. These figures show that liquid crystal for a right eye and a left eye of the conventional liquid crystal shutter glasses are positioned in one plane. In other words, when the viewer puts on the liquid crystal shutter glasses, both liquid crystal for a right eye 51R and liquid crystal for a left eye 51L become parallel to a screen of 3D display (not shown).
As regard to display which use liquid crystal particularly, the dependence on the visual angle has become a problem. That is, color and brightness of a screen change depending on an angle at which the viewer watches the screen and the direction in which the viewer watches the screen. This dependence on the visual angle is explained in FIGS. 11A and 11B. FIG. 11A is a sectional model view of liquid crystal pixel, and FIG. 11B is a graph showing the change of transmittivity (T) to the change of the voltage (V) when the transmittivity at a voltage of 0V is 100%. Characteristic A, characteristic of the front, and characteristic B in FIG. 11B respectively correspond to direction A, direction of the front, direction B in FIG. 11A. Liquid crystal has the dependence on the visual angle, so that, generally speaking, a screen may look white or black when viewed from the upper or lower direction.
Liquid crystal shutter glasses of FIGS. 10A and 10B composed of liquid crystal which have the dependence on the visual angle make it impossible to obtain the highest contrast to the screen direction of the 3D display. Insufficient contrast causes the following inconveniences. When liquid crystal for a right eye 51R transmits light and liquid crystal for a left eye 51L does not transmit light, the image for a right eye transmits the liquid crystal for a left eye 51L that should not transmit light and the images streams through the left eye of the viewer. When liquid crystal for a left eye 51L transmits light and liquid crystal for a right eye 51R does not transmit light, the image for a left eye transmits the liquid crystal for a right eye 51R that should not transmit light and the images streams through the right eye of the viewer. Occurrence of crosstalk obstructs adequate stereoscopic view.
As shown in FIGS. 10A and 10B, the common eyeglasses type of liquid crystal shutter glasses that the viewer's nose and ears hold liquid crystal shutter glasses portion and the goggle type of liquid crystal shutter glasses that rubber band or the like press down liquid crystal shutter glasses portion to the viewer's face are well-known as the conventional type of liquid crystal shutter glasses. Such liquid crystal shutter glasses as common eyeglasses type and goggle type, however, are awkward to use for those who put on eyeglasses.